Trap circuit for railway signaling systems



1932- D. w. MERSEREAU TRAP CIRCUIT FOR RAILWAY SIGNALING SYSTEMS Filed March 12, 1931 Nu E WZZMM ATTORNEY DONALD w. MERSEREAU, or ROCHESTER, NEW

Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE" SIGNAL COMPANY, OF

YORK, ASSIGNOR T0 GENERAL RAILVFAY ROCHESTER, NEW YORK TRAP CIRCUIT FOR RAILWAY SIGNALING SYSTEMS Application filed March 12, 1931.

This invention relates to a trap circuit for railway signaling systems, and more particularly to a trap circuit which is applicable to a comparatively short track section.

A trap circuit in railway signal parlance is an arrangement of track circuits and associated relays whereby the presence of a train in a particular section may be signified, even though a part of said section, of a length greater than the shortest train used, cannot be track circuited for local reasons, as, for instance, where there are one or more railroad crossings crossing such sections and prohibit track circuiting. In other words, a trap circuit is an arrangement of devices whereby section occupancy is indicated by the entrance of a train into such section, and clearing of such section is indicated bythe departure of such train, even though this train may occupy a non-traek-oircuited portion of such section for a time and during such occupancythis occupancy is indicated because the train has not yet departed. The particular embodimentof the invention illustrated is particularly applicable to a single track railroad, where a train may move in both directions, and wherein the signals for governing the movement of trains into a particular section are preferably manually controlled and are preferably interlocked in such a way that only one of these starting signals may be cleared at a time.

More specifically it is proposed in accordance with the present invention to employ atrack'circuit in the section under consideration on each side of an intermediate non-track circuitable portion, and to provide two stick relays for each of said track circuits, one of these stick relays being governed by the entrance of a train into sald track section and the other stick relay being deenergized upon the entrance of a train into that section, to gether with circuits and devices for restoring both of these stick relays only in the event that'a train has departed from the other end of said section with the track circuit at the entering end unoccupied.

Other objects, purposes and characteristic features of the present invention will in part be pointed out hereinafter and will in part Serial No. 521,905.

have been illustrated, of which the block 0 is still further divided into track circuit sections by insulating oints 6. As shown in the drawing the west end of the blockO is provided with a track circuit including the track battery 22 and the track relay 22T, whereas C the east end of the block 0 is track circuited by a track battery 23 and a track relay 23T, whereas the intermediate section of the block 0 is left non-track-circuited by reason of the presence of the cross tracks Track 1,Track J 2 and Track 3 shown. In this connection, it is of courseunderstood that the invention may be applied to other signaling problems, as, for instance, where a crossover between two parallel railway tracks is employed, and

where such cross over may have rusty rails prohibiting the use of the usual track circuit protection, or the invention may be applied under other circumstances where it is impossible to manifest the presence of a short 5 train, such as a gasoline motor car or for other reasons such as dirty rails. V 7 As illustrated, the starting signal 12 is employed to govern the movement ofeast bound trains into the single track section, whereas the leaving signal 14 is used to govern the movement of east bound trains out of the block 0, and the starting signal 13 is employed to govern the movement of west bound trains into the block 0, whereas the leaving signal 11 is employed to govern the movement of West bound trains out of the block 0. The signals 11 and 14 are controlled in accordance with trafiic conditions in advance thereof in the usual manner. P

It is believed expedient to first trace all of the normally closed circuits, as illustrated in the drawing, and thereafter consider the functioning of the various relays in response to the movement of a train through the block 0. 3

Under normal conditions, as illustrated in the drawing, a stick relay is energized through both of the following circuits :(1) beginning at the terminal of a suitable battery, front contact 16 of the relay 231:1 wire 17, front contact 18 of the relay 221T, wires 19, 20 and 21, winding of the relay 22L, wire 21, contact 25 of the signal 12 closed only when this signal assumes the stop position, wire 26 to the other terminal of said. battery, and beginning at the terminal of said battery, stick contact 27 of the relay 22L, wires 28 and 21, winding of the relay 22L, wire 2&, contact 25 of signal 12, and wire 26 back to the other terminal The stick relay 2251 is normally energized through both of the following circuit :(1) beginnin at the terminal of a suitable battery, 'l'lOllt contact 30 of the relay 22L, wires 81 and 32, winding of the relay 22TH, wire 33, front contact 3% of the track relay 22T to the other terminal of said battery, and beginning at the terminal of the same battery, stick contact of the relay 22T1 wires 36 and 32, winding of the relay 221 P, wire 33, front contact 3 1 of the track relay 22T to the other terminal Similarly, the relay 28L is normally energized through each of the following circuits :-(1) beginning at the terminal (-1- of a suitable battery, front contact 16 of the re lay 22TP, wire 17, front contact -18 of the relay 23TP, wires 19, and 51, winding of the relay 23L, wire 54, contact 05 of the signal 13 closed only when this signal assumes the stop osition, wire 56, to the other terminal of said battery, and (2) beginning at the terminal (f) of said battery, stick contact 57 of the relay 23L, wires 58 and 51, winding of the relay 23L, wires 5 1, contact of signal 13, wire 56, to the other terminal Also, the relay 28TP is normally energized through both of the following circuits :-(1) beginning at the terminal of a suitable battery, front contact 60 of the relay 23L, wires (31 and 62, winding of the relay 231?, wire 625, front contact 6d of the track relay 231, to the other terminal of said battery, and (2) beginning at the termi .al (-t) of the same battery, stick contact of the relay 23TP, wires 66 and 62, winding of the relay 23TP, wire 63, front contact (i l of the track relay 2ST, to the other terminal of said battery.

It is readily appa ent that the track rcaeater relay TPO for the Clitiic block O 18 1 1 l1 energized only in tne event that b "-h of the repeater track relays 22ll? o and 281? energized, namely through the follow in; circuit:-beginning at the terminal of a suitable battery, front contact 70 of the relay 22TP wire 71 front contact '[2 of the rela i 23TH wire 73, winding of the relay TPO to the other terminal Althoughthc starting signals 12 and 13 are not necessarily manually controlled, but are preferably interlocked so that only one of these signals can clear at a time, these signals 12 and 13 have been shown manually controlled by the polar control relay CR, which control relay is preferably controllable from a central oliice or dispatchers otlice DO, as ilzustrated by the line wire 75 and the lever L located in this central oflice DO, from which it is apparent that movement of the lever L to the right will energize the control relay CR to the right, this by reason of the flow of current of positive polarity, and movement of the lever L to the left will energize the con- LlOl relay C11 to the left, as through the medium of current of negative polarity. The clearing of these starting signals 12 and is of course, also dependent on tral'lic condi ions, not only of the block 0 but also of block next in advance of said block O the particular signal. In other words, 7 aring of the signal 12 depends upon u: conditions in advance of the s'gnal 1 1, and the cle r ng of the signal 13 depends on lli" co; ions in advance of the signal 11,

aitheugh this may be accomplished in any one of many different ways, it has been shown accomplished through the medium of si *nal contacts 77 and 78 associated respecti Jory with the signals 11 and 14.

Operation For the purpose of explanation, let us assume that there is an east bound train moving in the single track section N, and that the operator at the central ollice DO clears the signal 12 to allow this train to pass tnrough the single track section 0. This clearing of the signal 12 will be accomplished by movement of the lever L to the rfght hand pos tion, signifying east bound traliic and resul, g in the energization of the control Cit to the right, in which condition the signal 12 may clear through the following circuitz-beginning at the terminal (-1-) of a suitable battery, contact 78 of the signal 14 closed only when this signal 14 assumes either the clear or caution position, wire 80, front contact 81 of the relay TPO, wire 82, polar contact 83 of the relay CR, wire Bl, mecha- Minn of the signal 12, to the other terminals of said battery. Clearing of the signal 12 opens the contact 25 so that the stick relay 22L is decnergized.

It is desired to point out at this juncture that if the operator in the central oflice D0 in the meantime has changed his mind and wishes to put the signal 12 back to the stop position, th s return of the signal 12 to the stop position will effect reenergization of the stick relay 22L, this because the pick-up circuit for said stick relay 22L and including the contacts 18 and 16, respectively, of the relays 221? and 23TP is closed. Attention is also direct d to the fact that even though the stick With the track relay relay 22L has by its dropping opened its contact 30, that the relay 22L is not de energized, because the second circuit for this relay 22TP which includes the contacts 34 and 35 is still intact.

Proceeding, on the assumption that the operator leaves the signal 12 in the clear position, let us now observe the effect of the entrance of an'east bound train into the block 0. The entrance of the east bound train under consideration into the block 0 effects deenergization of the track relay 22T, there by deenergizing the relay 22T'P, and deenergization of the relay 22TP by the opening of its contact 70 effects deenergization of the repeater relay TPO for the block 0.

f we assume that the east bound train under consideration is so short that theitrack relays 221 and 28T are both energized while this train is occupying the un-track-circuited portion of the block 0, then even under this consideration, namely, with the track relays 22T and 23T energized,the relay TPO remains deenergized, this because one pick-up circuit for the stick relay 22L is open at the contact 18 of the relay 22TP, and the other piok=up circuit for the relay 22L is open at the back contact 16 of the relay 23TP. Also, the pick-up circuit for the relay 22TP is open at the back contact 30 of the relay 22L, so that both of these relays 22L and 22TP will remain deenergized.

, Let us now assume that the short train under consideration continues its movement in an easterly direction and treads upon the track circuit containing the track relay 23T. It is of course understood that since the relay TPO is now deenergized that the signal 12 has again been operated to its stop position. 23T now deenergized, the following pick-up circuit for the relay 22L is closed z-beginning at the terminal back contact 16 of the relay23TP, wires 86, and 21, winding of the relay 22L, wire T 24, contact 25 of the signal 12, wire 26 to the other terminal With the relay 22L now energized it will be stuck up through its stick contact 27 and remain energized irrespective of the opening of the back contact 16 of the relay 23TP. Also, closing of the contact 30 of the relay 22L will effect reenergization of the stick relay 22TP, this because the contact 34 of the track relay 22 has been reclosed. Attention is directed to the fact that the east bound train by its deener 'ization of the track relay 23T did not efi zzct deenergization of the stick relay 23L but merely effect deenergization of the repeater track relay23TP. It is thus apparent that the relay TPO remains deenergized until the departing train has left the track circuit containing track relay 23T, and when this occurs the trackrelay 23T is reenergized and efl'ects reenergization of the relay 23TP, through the medium of the front contact 72 of which the relay TPO is energized as soon as the east bound train under consideration has left the block 0.

It is thus apparent that the relay TPO does not only indicate occupancy of one or the other or both of the track circuits included in the block 0, but also indicates whether a train which entered one end of the block 0 has departed from the other end of this block. Furthermore, the function of definitely indicating the occupancy of a particular block in spite of the presence of a non-track-circuitable section in such block these functions are carried out without the provision of additional insulating joints or other means for indicating the departure of a train, that is, only two insulated track sections, one on each side of the non-track-circuitable section, are required. It is of course understood that since the apparatus shown at the east end is identical to the apparatus shown at the west end of the block 0, that a west bound train will be manifested during its occupancy of the block in exactly the same way as already explained in connection with the movement of an east bound train, and for this reason certain like parts at the east end of the block 0 have been designated by corresponding reference characters with an exponent one.

It should be understood that the trap circuit under consideration may be used for indicating occupancy of a particular track section at other locations, such as at cross-overs, and that this same meansmay be employed for effecting approach locking in connection with switch machines for controlling the points of such cross-overs, and that the invention may be applied to other types of railway signaling systems than the particular one illustrated, in the same way as ordinary track relays are employed in other signaling systems, all without departing from the spirit or scope of the present invention. Also, it is desired to be understood that the particular embodiment of the invention illustrated has not been selected fort-he purpose of showing he precise manner in which the invention must be applied nor has it been selected for the purpose of showing the scope of the invention, and it is further desired to be understood that various changes, modifications and additions may be made to adapt the invention to the particular problem encountered in practicing the same, all without departing from the spirit or scope of the invention or the idea of means underlying the same, except as demanded by thescope ofthe following claims.

What I claim as new is 1. A trap circuit for a track section of a railway signaling system in which there is an intermediate portion which can not be track-circuited comprising, a normally closed track circuit including atrack relay for each of the two end portions of said section, a

stick relay for each of said end portions, and means including said track relays ior dropping one of said stick relaysupon the entrance of a train into one end of said section and for picking up such stick relay upon departure of a train from the other end of said section.

2. A trap c railway signa mediate pr uited coiu g, a normally closed track circuit inclu ll track relay for each of the two end portions of said s stick relay for each of said end pirtions, means including said track relays for dropping one of said stick relays upon the entrance of a train into one nd of said section and for picking up such parture of a train iron the 5, section, and a repeater relay 0 if both of said stick relays ii trap circuit for a a track section of a in in which there is which can not be railway anng s "StQll'l in whi-cl interined )ort-i, l which can not be trackiicuiied a normally closed track circuit i track relay for each of the t\ s end '0 s oi": said. section, two

' each of said end portions the h can be plcked is en stick relays second S'UlCiI up only if ergized and he associat ergized and w re said track relay is on picking up the departire of i said section.

i. A trap circuit for a track section of a railway signaling system in which there is an intermediate portion which can not be trackcircuited comprising, a normally closed track circuit including a track relay for each of the two end portions of said section, two stick relays for each of said end portions the s 0nd stick relay of which can be picked up only if the first of said stick relays is encrgized and the associated track relay is energized and will remain stuck up so long as said track relay is energized, means for picking up the first of said stick relays upon departure of a train from the other end of said section, and a repeater relay energized only if said two second stick relays are energized.

5. In a trap circuit for railway signaling systems, the combination with a section of track having a portion which cannot be trackcircuited, an insulated track circuited section on each side of said portion each of which includes a normally energized track relay, a stick relay associated with. each of said track relays, and means including said track relays for dropping the stick relay at one end if a train enters that end of said section of track and for again picking up said stick relay s l v Llfl ck relays upon c other end of when said train departs from the other end of said section of track.

6. In a trap circuit for railway signaling systems, the combination with a section of track having a portion which cannot be trackcircuited, an insulated track-circuited section on each side of said portion each of which includes a normally energized track relay, a stick relay associated with each of said track relays, and means including said track relays for dropping the stick relay at one end if a a train enters that end of said section of track and for again picking up said stick relay when a train departs from the other end of said section of track with said one end of said section unoccupied.

7. In a trap circuit for railway signaling systems the combination with a section of 7 n track having a portion which cannot be trackcircuited, an insulated track-circuited section on each side of said portion each of which in.- cludes a normally energized track relay, a stick relay associated with each of said track relays, and means including said track relays for dropping the stick relay at one end if a train enters that end of said section of track and for again picking up said stick relay when a train departs from the other end of said section of track with said one end of said section unoccupied, and another relay energized only if both of said stick relays are energized.

8. In a trap circuit for railway signaling systems, the combination with a section of track having a portion which cannot be trackcircuited, an insulated track-circuited section on each side of said portion each of which includes a normally energized track relay, a signal governing the entrance of trains into one end of said section of track, a first stick relay energized only it said signal is at stop, a second stick relay energized only if the track relay at said one end is energized and which can be picked up only it said first stick relay is energized, and means for picking up said stick relays upon deenergization of said other track relay.

9. In a trap circuit for railway signaling systems, the combination with a section of track having a portion which cannot be trackcircuited, an insulated track-circuited section on each side of said portion each of which includes a normally energized. track relay. a signal governing the entrance of trains into one end of said section of track, a first stick relay energized only if said signal is at stop, a second stick relay energized only if the track relay at said one end is energized and which can be picked up only if said first stick relay is energized, and means for picking up said stick relays upon deenergization of said other track relay providing said one track relay is then energized.

10. A trap circuit for railway signaling systems comprising; a block including a track-circuited section including one track relay, an intermediate non-track-oircuited section and a track-cirouited section including another track relay; a block relay; and

means for deenergizing said block relay effective upon deenergization of said one track relay, and efi'ective to reenergize said block relay upon deenergization followed by reenergization of said another track relay.

11. A trap circuit for railway signaling systems comprising; a block including a track-circuited section including one track relay an intermediate non-track-circuited section and a track-circuited section including another track relay; a block relay; and means for deenergizing said block relay effective upon deenergization of said one track relay, and effective to reenergize said block relay upon deenergization followed by reenergization of said another track relay providing said one track relay has been reenergized in the meantime. 1

In testimony whereof I afiix my signature.

DONALD W. MERSEREAU. 

